The patent document CH-A-66541 describes a hollowed out caseband enclosing a watch movement. This caseband also exhibits a first support surface cooperating with a crystal and a second support surface cooperating with a back cover. These first and second support surfaces however are not cylindrical but conical, since crystal and back cover are snap fitted onto the caseband. Furthermore, the movement is maintained in place within the caseband without the help of blocks which would take up space in the recess of the caseband as will appear in the present invention. The construction proposed in the cited document is above all intended for a pocket watch in which no particular arrangement is made in order to diminish the thickness of the watch or to reduce to a minimum the weight of the material making up the caseband, as is the case in the invention to be described, where the caseband may be formed of precious metal in diminishing as much as possible the weight of this metal.